Variations in the Rate of Anaerobic Succinate Accumulation within the Central and Marginal Regions of an Euryoxic Bivalve Mantle     

Ed  Greenfield Miles A.  Crenshaw 《Marine Ecology》1981,2(4):353-362

Abstract. Anaerobic metabolism in the central and marginal portions of the mantle of Mercenaria mercenaria was compared. Anaerobic succinate accumulation was more rapid in the central region. This difference may be due to higher phosphoenolpyruvate carboxykinase activity in the central region. Thus, the central region is more specialized for anaerobic metabolism and the marginal region more for net shell growth. The original rate of succinate accumulation in the mantle is similar in isolated mantles and intact clams, suggesting that mantle succinate production does not require translocation of precursors from other tissues. However, in intact clams, the rate of succinate accumulation in the central region of the mantle slows after four hours. The reduced rate is probably caused by reducing the metabolic rate. Succinate accumulation and shell dissolution are slower in freshly collected clams than in clams that had been stored anaerobically. The difference may be due to induction of PEPCK synthesis during storage. Shell derived calcium did not accumulate in the mantle and, therefore did not alter the intracellular calcium concentration in the mantle.  相似文献   

The Levant Slumps and the Phoenician Structures: collapse features along the continental margin of the southeastern Mediterranean Sea     

Yossi Mart  William Ryan 《Marine Geophysical Researches》2007,28(4):297-307

Two distinct series of slumps deform the upper part of the sedimentary sequence along the continental margin of the Levant. One series is found along the base of the continental slope, where it overlies the disrupted eastern edge of the Messinian evaporites. The second series of slumps transects the continental margin from the shelf break to the Levant Basin. It seemed that the two series were triggered by two unrelated, though contemporaneous, processes. The shore-parallel slumps were initiated by basinwards flow of the Messinian salt, that carried along the overlying Plio-Quaternary sediments. Seawater that percolated along the detachment faults dissolved the underlying salt to form distinctly disrupted structures. The slope-normal slumps are located on top of large canyons that cut into the pre-Messinian sedimentary rocks. A layer of salt is found in the canyons, and the Plio-Quaternary sediments were deposited on that layer. The slumps are bounded by large, NW-trending faults where post-Messinian faulted offset was measured. We presume that the flow of the salt in the canyons also drives the slope-normal slumps. Thus thin-skinned halokynetic processes generated the composite post-Tortonian structural patterns of the Levant margin. The Phoenician Structures are a prime example of the collapse of a distal continental margin due to the dissolution of a massive salt layer.  相似文献   

琉球群岛东部海区表层沉积物中浮游有孔虫分布及指示意义     

吴永华  程振波  石学法  李小艳  石丰登  鞠小华 《海洋地质与第四纪地质》2007,27(6):1-7

对琉球群岛东部海区123个表层沉积物样品中浮游有孔虫因子分析结果表明,浮游有孔虫组合在溶跃面以上表现为Globigerinoides ruber-Globigerinata glutinata组合,溶跃面以下为Globorotalia inflata-Neoglobo-quadrina pachyderma (dex.)组合,局部受黑潮影响区域黑潮标志种Pulleniatina obliquiloculata含量相对丰富,为Neogloboquadrina dutertrei-P.obliquiloculata组合;表层沉积物中浮游有孔虫的丰度及组合分布特征对于碳酸盐溶跃面深度及碳酸盐补偿深度有一定的指示意义。另外,碳酸盐保存特征研究表明,该区域现代碳酸盐溶跃面深度约为3100 m,碳酸盐补偿深度约为4300 m。  相似文献   

海上矿石运输最优船队的组建     

董胜 《中国海洋大学学报(自然科学版)》1997,(2)

针对海上矿石运输，介绍了一种完成定量任务并能使投资费用最少为目标的最优船队组建方法，同时对易变参数进行了灵敏度分析，使决策更加科学化  相似文献   

Nature of the connection between the Northern and Southern Zechstein Basins across the Mid North Sea High     

M.K. Jenyon  P.M. Cresswell  J.C.M. Taylor 《Marine and Petroleum Geology》1984,1(4):355-363

The seismic expression of a salt-filled channel which cuts across the Mid North Sea High in Quadrant 37 is described, with features interpreted as being produced by salt-edge dissolution forming both eastern and western margins of the channel. The apparent half-graben nature of the channel is shown to be only superficial, and due to complex faulting associated with, but not defining, its western margin. The shallower faulting here is a Mesozoic to early Tertiary growth fault related to local dissolution of Zechstein salt. The dissolution effect appears in turn to have been localized by the presence of a deeper fault that was already downthrown to the east in Zechstein times, when it seems to have limited the eastward progradation of Zechstein shelf carbonates and anhydrites, and had probably ceased to move significantly before the onset of the Late Cimmerian erosional phase. The origin of this arcuate fault is tentatively ascribed to subsidence around a granite batholith. Zechstein salt originally spread some distance to the east and west of the channel; it was dissolved from the edges inwards, mainly before the Late Cretaceous, giving rise to a thicker Mesozoic sequence on parts of the flanks of the channel than in the middle. Besides providing an interesting structural case history, the features described have implications regarding Zechstein sedimentation, reservoir potential, the tectonic history of the North Sea, and the nature of the Mid North Sea High itself.  相似文献   

直升机大比例尺航空物探在深部找矿中的应用前景   总被引：4，自引：1，他引：3  

熊盛青  于长春  王卫平  范正国  王乃东  万建华  张洪瑞 《地球科学进展》2008,23(3):270-275

为克服深部及矿区外围地面物探工作难度大、勘探周期长等不利因素,探讨了利用直升机快速获取高分辨率航空物探资料的方法。以成功应用实例,总结了直升机航空物探方法技术的特点和优势,并针对目前深部找矿工作区的部署特点,展望了直升机物探利用磁、电、能谱综合信息,挖掘矿山深部及外围资源潜力,直接为地质找矿服务的应用前景。  相似文献   

拉拉铜矿黄铁矿微量元素地球化学特征及其成因意义   总被引：6，自引：0，他引：6  

周家云  郑荣才  朱志敏  陈家  沈冰  李潇雨  罗丽萍 《矿物岩石》2008,28(3)

四川会理拉拉铜矿床是我国著名大型富铜矿床,针对该矿床中黄铁矿的微量元素、稀土元素地球化学分析表明:拉拉铜矿经历了早期火山喷发成岩成矿和晚期变质成岩成矿作用.条带状矿石中的黄铁矿Co/Ni比值集中于4.92～79.2之间,落入火山成因黄铁矿区,稀土元素分布具有Eu正异常和轻稀土富集的特征,反映矿床具有伴随河口群火山喷流沉积成岩过程的同生沉积成矿作用.脉状矿石中的黄铁矿Co/Ni比值集中于1.10～3.45,落在热液成因黄铁矿区,稀土元素较河口群岩石及其他典型块状硫化物矿床矿石稀土元素更加富集轻稀土元素,稀土含量变化范围更大,显著的负Eu异常,则又说明,矿床形成的主要成矿作用是伴随新元古代晋宁运动而发生的大规模的变质作用.  相似文献   

热液锆石U-Pb定年与石英脉型金矿成矿时代:评述与展望   总被引：4，自引：0，他引：4  

毕诗健  李建威  赵新福 《地质科技情报》2008,27(1):69-76

石英脉型金矿床是最重要的金矿床类型之一,对其成矿时代的精确测定却一直是一道难题.近年来同位素质谱技术的发展使得通过含金石英脉中热液锆石的U-Pb定年来精确限定石英脉型金矿床成矿时代成为可能.但含金石英脉中的锆石组成通常较复杂,除有热液锆石外,还可能出现从围岩中捕获的岩浆锆石和变质锆石.锆石成因和组成的这种复杂性,经常导致所获得的U-Pb年龄数据难以解释或缺乏明确的地质意义.因此石英脉型金矿床锆石U-Pb定年的关键是有效区分从成矿流体中直接生长的热液锆石和从围岩中捕获的岩浆锆石或变质锆石.通过锆石形貌、结构、微量元素组成(含稀土元素)、矿物或流体包裹体特征等的系统分析和综合研究,可以较好地区分含金石英脉中的不同成因锆石.在此基础上利用先进的SHRIMP或LA-ICPMS锆石U-Pb分析技术对石英脉中的热液锆石进行微区原位定年,可以获得石英脉型金矿床可靠的成矿年龄.  相似文献   

火山热液型铅锌矿床岩石地球化学特征及预测指标   总被引：2，自引：1，他引：1  

刘崇民  马生明  胡树起  王之峰  汤丽玲  李冰 《物探与化探》2008,32(2):154-158

火山热液型铅锌矿床赋矿围岩、后期脉岩和蚀变岩石中成矿元素铅锌银含量高,矿体元素组合复杂,原生异常发育,并存在着原生分带现象。矿体前缘元素为I、Hg、As、Sb、B、Ba;近矿指示元素是Pb、Zn、Ag、Au、Cd、Mn、Cu;尾部或矿下指示元素为Cu、Mo、W、Sn。根据矿床指示元素的分布规律和原生晕的分带性,研制了判别矿床剥蚀程度和评价异常的地球化学指标,建立了该类矿床的地球化学找矿预测标志。  相似文献   

黔西北威-赫-纳-织-水地区铅锌(铜)矿带上 重力异常反映的地质信息   总被引：4，自引：1，他引：3  

王亮  乔计花  龙超林 《物探与化探》2008,32(4):374-378

研究黔西北威宁—赫章—纳雍—织金—水城地区,铅锌(铜)矿带上分布的1∶20万区域重力异常特征,及其与地质、构造、岩体、化探等异常的对应规律及其关系,能对该区此类矿产的成矿规律、成矿部位和成矿特点的研究有所帮助,提出下一步找矿方向上的参考建议。  相似文献